File your Arts Tax return online. Pay your tax due with Visa, Mastercard, Discover Card, ACH payment, or mail a check or money order.Prepare - The online system gives you 30 minutes to complete your report. If you go beyond this you may get "timed out. Check out answers to your questions about Portland's unique tax forms. You can then easily file your Portland taxes with TaxAct. Withholding certificate. Note: It is important to download and save the form to your computer, then open it in Adobe Reader to complete and print. After you download the waiver, please print it, fill it out and mail it to LWV of Portland, PO Box 3491, Portland OR 97208-3491. In Oregon, the highestprofile of those may be the bond ask for the Portland zoo.